I've read various rants about the quality of the various ingredients we use in DIY e-juice. Chinese Nicotine Vs. American made Nicotine, Propylene Glycol from the 'Feed Store', Glycerin from Wally World, and now Flavor additives.
SOoo, why not just 'One more rant'?
From 'way back' when I started doing my own DIY e-juice I was more concerned about the TRACEABILITY of the MAJOR INGREDIENTS like PG and VG. The potential for strange contaminants, on a purely 'percentage' basis, justs seems higher for the major ingredients. I posted my views on PG and VG in the past. Go find my old threads if you want.
While some chemical processes have dangerous by-products that could remain in the final product, the chance of getting 'free extra chemicals' seems to me to be more of a 'human error' factor. We've seen this is many automated food processes where the 'system' is not completely cleaned before a different product is processed (frequently in U.S. food processing plants). The chance of contamination or errors in the quantities of ingredients just seems more likely when multiple products are processed with the same equipment, or when a product contains several ingredients. PG and VG are usually processed in 1000 gallon batches, contain only one ingredient, and when purchased 'close' to the source, have minimal 'human' intervention.
I'm sure that most vapers have a concern over vaping Chinese chemicals and that has driven some vendors to claim "Made in the USA" as an assurance of getting a high quality product. Based on reported errors in many U.S. facilities, I'm not so sure about that. But, none the less, made in the USA is an advertising point.
Back to the point. What ingredients have the highest potential for the introduction of 'Strange Chemicals'?
A percentage breakdown of my typical DIY batch of e-juice:
40 to 45% Vegetable Glycerin,
40 to 45% Propylene Glycol,
8 to 10% Flavoring,
3 to 6% Water,
Note that the smallest ingredient is the Nicotine.
If I am careful about the source of my PG and VG, then the ingredient with the next highest percentage is the FLAVOR.
After the PG and VG, the next most likely source of dangerous unknown substances, IMHO, is the flavorings added to e-juice. I have eliminated flavors with lots of extra coloring, and those that use unknown proprietary recipes (except my RedBull) to minimize the unknown ingredients put in 'on purpose'.
Why then would someone hype Chinese flavors over U.S. made flavors after making such a 'Big Deal' about U.S. made Nicotine? The 'sheep' do seem to be happy about it though